Central Nervous System Depressants and Risk of Hospitalization due to Community-Acquired Pneumonia in very Old Patients

Background: Central Nervous System (CNS) depressants like antipsychotics, opioids, benzodiazepines and zolpidem are frequently used by patients of a wide range of ages. Uncertainty remains about their effect in very old adults (>80 years old) and their potential for pharmacodynamic and pharmacokinetic drug-drug interactions in this population. Objective: To assess if the use of CNS depressants is associated with a higher risk of hospitalization due to community-acquired pneumonia (CAP) in very old patients. Methods: In this prospective study, 362 patients over 80 years of age who had been consequently admitted to the general ward of a teaching hospital were examined. Each patient was assessed, by our pharmacovigilance team within 24 hours of admission, to identify outpatient medication use and potential drug-drug interactions. Results: The overall use of CNS depressants as a group was not associated with a higher risk of admission due to CAP in very old patients (55% vs. 49%; OR=1.28 [0.76-2.16], p=0.34). However, the use of antipsychotics was associated with a higher rate of admissions due to CAP in this population (OR=1.98 [1.10-3.57], p=0.02). No association was seen between opioids (p=0.27), zolpidem (p=0.83), or benzodiazepines (p=0.15) and the rate of admissions due to CAP in these patients. Moreover, pharmacodynamic or pharmacokinetic interactions leading to CNS depression were equally found in patients admitted for CAP and those admitted for other reasons. Conclusion: The use of antipsychotics in very old adults was associated with an increased risk of hospital admission due to CAP. This suggests that the use of these medications in this population should be done with caution. No association was observed with opioids, benzodiazepines and zolpidem with the latter outcome.